This invention relates to a recorded data reproducing apparatus for use with hard disk devices, and more particularly to a recorded data reproducing apparatus having simple circuitry, and which is easy to assemble and adjust.
In hard disk devices, the level of the signal read out from a magnetic head changes according to the track or cylinder position on the magnetic recording medium. Specifically, when the magnetic head is positioned above an inner track on the magnetic recording medium, the signal level is low. When it is positioned above an outer track, the signal level is high. In order to use such signals output from the magnetic head, for subsequent data processing, the varying signal level must be adjusted to an appropriate level.
To cope with this problem, the conventional recorded data reproducing apparatus for use with a hard disk device performs gain adjustments, using an auto-gain control (AGC) generator. To adjust the gain, the signal, amplified by an amplifier, is rectified and smoothed, and is then supplied to the AGC generator. The AGC generator outputs an AGC signal to the amplifier, in accordance with the input; thus, the amplified signal is fed back to the amplifier.
The AGC generator, however, requires complicated circuitry. To perform gain adjustment of the amplifier of the AGC generator, manual operation by means of a variable resistor is required. There are many problems in which the number of assembly steps of the apparatus is increased, and the assembly is thus complicated.